Never had an animal inside the car but over the years I had wasp nets inside the door jams of my Ford Van tow vehicle and bird nests built under the hood 3 years in a row. One year under the brake master cylinder, next on top of the battery, and then one under the brackets that holds the battery.
I finally got smart and put a piece of screen in front of the grill when it sits in storage and no more birds nests!